Police cordoned off large sections of two neighbouring parks in an investigation into an incident involving a young woman.
Officers launched a probe after a 20-year-old woman was found in a distressed state by a friend in Weston Park, Sheffield at around 2am this morning.
Large sections of Weston Park and Crookes Valley Park were closed off to the public for several hours while police examined the areas.
They green spaces were re-opened during the afternoon but patrols have now been stepped up in the area.
A spokeswoman for South Yorkshire Police said the woman is helping them with enquiries and they are now using CCTV footage to trace her movements to establish what happened.